1. Field of the Invention
The present invention relates to a V-belt type continuously variable transmission and, in particular, to a V-belt type continuously variable transmission in which cooling air is supplied in the inside.
2. Description of the Related Art
In a V-belt type continuously variable transmission, the inside of the transmission case is provided with: a drive pulley; a driven pulley; and a V-belt wound around between both pulleys. The transmission case is provided with an inlet opening and an outlet opening. Then, cooling air supplied through the inlet opening to the transmission case is guided from the drive pulley side to the driven pulley side and then discharged through the outlet opening. By virtue of this, the inside of the transmission case is cooled.
For example, Japanese Patent Publication No. 2010-151237 discloses a V-belt type continuously variable transmission in which an air intake port is provided in the outer periphery of a transmission case and a centrifugal fan is provided in the rear face of a sheave on the engine side of the drive pulley. The air intake port is arranged so as to be oriented approximately to the air inlet part in the inner side of the radial direction of the centrifugal fan, that is, arranged approximately in parallel to the shaft axis of the drive shaft. Then, the air inlet part is connected to an air intake duct for acquiring cooling air from the front. By virtue of this, cooling air is taken in from the front through the air intake duct and then supplied to the air inlet part of the centrifugal fan.
Meanwhile, when the cooling air is to be taken in from the side on the engine side of the V-belt type continuously variable transmission, the air intake duct need be arranged so as to bypass the engine from the side on the engine side and then extend to the air inlet part in the outer periphery of the transmission case. This causes the air intake duct to become longer.
On the other hand, when for the purpose of shortening the path of the air intake duct, an inlet opening is provided in the side surface on the engine side of the transmission case and then the air intake duct is connected to the inlet opening, with departing from the connection part with the engine, the inlet opening is arranged at a position deviated from the shaft axis of the drive shaft. As a result, the air intake passage from the inlet opening to the air inlet part of the centrifugal fan needs to be bent approximately at a right angle. This causes a rise in the pressure loss in the air intake passage and hence a decrease in the amount of cooling air supply.